Many commercial buildings have air handling units, usually placed on the roof of the building. An air handling unit of the prior art is generally shown in FIG. 1.
As can be seen, a typical air handling unit includes an enclosure E with one or more doors D to allow personnel to gain access to the machinery inside the enclosure.
The air handling unit enclosure typically encloses heating, ventilation and air conditioning equipment (HVAC). Because the HVAC equipment is used to maintain the building's temperature, it is important that the enclosure E and doors D of the air handling unit do not allow the passage of air into or out of the air handling unit.
Because of this requirement, the air handling unit must be able to withstand the high external air pressure associated with gale force winds. Furthermore, the air pressure inside the air handling unit is typically lower than ambient air pressure outside the unit (sometimes by as much as six inches), and such a difference in air pressure can cause a pressure differential between the inside and outside of the unit equivalent to up to a 300 mph wind blowing against the unit and its doors. The doors must not leak air, even under such a high pressure.
In addition, the doors of the unit must have thermal insulation to prevent heat exchange between the outside and the inside of the unit.
Typical air handling units of the prior art are capable of withstanding six inches of pressure differential, but this is their limit.
In today's environment, there is a need for high-efficiency cooling in buildings. Such high-efficiency cooling requires a more efficient air handling unit, because colder air within the air handling unit means that less volume of air conditioned air is needed to maintain the building's temperature.
There is a need for a high-efficiency air handling unit with higher structural strength and more efficient thermal properties.